Jeff Nelson believes he is as strong as he has ever been during the postseason, when his omnipresent curveballs are particularly effective.

“The operation was more like a car getting a 50,000-mile checkup and getting new oil,” Nelson said. “When you pitch as much as I do, you’re always going to have stuff in your arm. Hopefully [the operation] will keep me going for a few more years.”

Since arriving in The Bronx before the 1996 season, Nelson has been a staple in the Yankee bullpen. For some time this year, though, Nelson’s future was in doubt.

The 6-foot-8 right-hander had arthroscopic surgery on his right elbow on June 8. But Nelson was able to come back quickly and finish the season healthy. The culmination of that comeback came on Tuesday when he pitched a scoreless ninth to finish off the Yankees’ 8-0 win over the Rangers in Game 1 of the Division Series.

“It was great to be out there in a big situation again,” Nelson said before Game 2 at the Stadium last night. “It helped that I was able to come back quickly and get comfortable again.”

Originally, doctors told Nelson that surgery might shelve him for the duration of the season. The injury that plagued him throughout May didn’t go away with rest, so Nelson opted to have the bone spurs cleaned out in his elbow.

“I’ve had [the surgery] before, so I was confident it would work,” said Nelson, who also went under the knife after the ’96 season. “But I was shocked how quickly I was able to get back.”

Nelson began tossing the ball just four weeks after the surgery, two weeks before doctors thought he would be able. The Yankees didn’t expect Nelson to return until Sept. 1, but he came off the DL on Aug. 11. The prompt return helped Nelson down the stretch.

“I was kind of uncomfortable after the operation,” said Nelson, who has appeared in the postseason every year since 1995. “It wasn’t like the pain beforehand, but surgery always has an effect on you. It was important for me to get my feet wet and prove to the guys that I could pitch every day and not just once in a while.”

He erased any doubt of his durability when he pitched in six out of seven games from Sept. 21-27. Nelson allowed just one run and struck out five in 3 innings over that stretch.